If you are using the Code Contracts library in your application you may from time to time run into some weird build errors. Today I ran into a fun one as well. While building my code I received the following error in my error window:

Of course I checked my output window but at first nothing seemed obvious. And of course being a guy (aka stubborn and stupid : ) ) I figured a Clean and Rebuild would do the trick, but as you may have guessed it did not.

Given that I was still not able to get it to compile I decided to take a deeper look at my output window. While sifting though the mountain of output data I was able to find one line which lead me to the following:

Long story short it appears that my .pdb file is out sync with my .dll. Once I removed/deleted the pdb I was able to perform a rebuild and the world is a happy place.